16th February 2015 Reports of sow-thistles germinating in winter oilseed rape and cleavers not as well controlled as they should be from autumn applications add up to the need for a targeted post-emergence herbicide to tidy crops up and avoid problems at harvest. As well as being visible at flowering, these problem weeds compete directly and smother the crop, making harvesting physically more difficult, and increasing the risk of weed seed contamination and hence admix penalties

Applying post-emergence herbicides to winter wheat to combat blackgrass is the vital last step in the autumn programme to fight this pernicious weed, says Dow AgroSciences.

Mild temperatures and plenty of rain across much of the UK have encouraged rapid growth of both crops and grassweeds. In crops drilled early weeds are thriving as the very dry September conditions mean that pre-emergence herbicide activity has been reduced.

Dow AgroSciences is pleased to inform growers and advisors that CRD has granted an approval for AstroKerb to allow the straw from oilseed rape crops treated with AstroKerb to be burnt for heat or electricity production. The following updated statement will now appear on the label : “DO NOT remove oilseed rape straw from the field unless it is to be used for burning for heat or electricity production.”

In this Edition

This Edition’s FAQ:What can I add to Atlantis WG for cleavers? Why has Galera (MAPP 16413) got a 36 month following crop restriction? What can I plant after failed oilseed rape?

The “three” crop rule and cereal herbicides

CAP reform and greening is forcing changes to rotation and future cropping. Beans and peas are attracting particular interest. Integrating what may be sudden changes of rotation with past herbicide use in preceding crops will be vital. Minimising future headaches now, will be a positive move.

In autumn 2015, cereals, oilseed rape, field beans, red and white clover or grass may be sown to succeed a cereal crop treated with UNITE. Next spring 2016, there are no restrictions at all on crops.

So winter or spring field beans or peas are a following crop option with UNITE. Also remember there are no additional cultivation requirements for drilling crops like oilseed rape where direct drilling is desired.

Grassweed solutions for late drilled winter wheat

Many have drilled late as an approach to improving blackgrass control across the rotation. In addition now beet has been lifted more winter wheat has been drilled over January and February.

Late drilling usually means lower yields compared to crops in the autumn, however this year as ever there will be a real focus on minimising production costs which UNITE with its grass and broad-leaved spectrum will help meet. In either situation grassweeds are likely to be small and as soils warm, broad-leaved weeds will germinate and grow.

As well as controlling blackgrass, bromes, ryegrass and any wild oats, UNITE will also control many yield-robbing and rotational problem weeds such as cleavers, cranesbill, poppy, speedwell, charlock, groundsel, volunteer rape, volunteer beet and many others – perhaps saving a further spend on other broad-leaved weed herbicides and alleviating pressure tank mixing with fungicides later in the programme.

UNITE can be mixed with chlorothalonil e.g. Bravo 500 if you want to get the T0 on as well.

Planning to treat ryegrass with Broadway Star?

Ryegrass is becoming more difficult to control. It’s a common grassweed in parts of the country such as Shropshire, Kent and Yorkshire but surprisingly enough can also be the key driver-weed in traditional “ blackgrass” areas such as Essex. Autumn germinating ryegrass is particularly competitive.

Late applications will lead to variable or poor control. Endeavour to apply Broadway® Star early at T0 when actively growing as grassweeds in advanced stages of growth at late tillering /stem extension onwards, are more difficult to control. This will remove weed competition early before canopies close-in preventing good spray coverage and mean less complicated tank mixes at T1 and T2.

Sudden changes in temperature, presence of EMR and drying soils can all affect the level of control achieved. Weed growth and stage continues to be the biggest efficacy driver. Most consistent ryegrass control occurs from earlier applications.

Groundsel

This weed, particularly the common form, Senecio vulgaris, is cropping up more and more in arable rotations across the UK.

Seeds germinate throughout the year and seed shed can mean more than one generation a year even though it is an annual. It can flower within about 6 weeks of emergence and its speedy growth habit can catch many out. Seeds are dispersed by wind. It prefers loamy soils or sandy soils with a pH above 6.0.

Although not on label, Galera®, Dow Shield® 400 and ASTROKerb® all control groundsel in oilseed rape. Again not on label but Broadway Star controls it up to flowering. Groundsel is on-label for UNITE up 6 etl. Spitfire® does it to 50 mm again off label at 1.0 L/ha, but you will get better control if you tank mix with CMPP, HBN or with a dicamba+ mecoprop mix. Watch that speedy growth habit!

Galera MAPP 11961 – Use up on farm stocks this spring. This can be applied in February

Galera MAPP 16413 – Application is from 1st March

Galera should not be applied until large variations in day/night air temperatures have passed (i.e. no frosts)

Applications should be made to a dry leaf

Galera is rainfast after a period of 6 hours drying

Control of cleavers is maximised when applications are made just before crop canopies close

With such obvious populations of broad-leaved weeds present in oilseed rape crops, the temptation is get out early and treat with Galera, but caution is required. To optimise performance, stable air temperatures are required of at least 6oC and rising, but preferably 8oC or higher. The warmer and more stable the conditions, the better the results are likely to be. Warm days and cold nights (high diurnal variation) are likely to give poor results, particularly against cleavers.

Another issue at this time of year can be wet leaves. Galera needs 6 hours drying time, after application to a dry leaf, for best results. A breeze to dry the plants off in the morning and a planned application during the warmest part of the day is the approach most likely to give good results. That is why having the appropriate fields identified and the required amount of Galera on farm and ready to apply is so important. With the cut off of flower buds visible above the crop canopy, the opportunities to spray can be limited.

Regulation is causing greater restriction in what we can all do on farm; this is especially true of pesticides. When Galera was re-registered tighter regulatory requirements in relation to residues in following crops meant that the following advice appears on label:

FOLLOWING CROPSFollowing application of Galera the following restrictions on planting the following crops must be observed:Wheat, barley, oats, maize, oilseed rape: 4 months (120 days)All other crops: 36 months (3 years)

This new restriction is not because Galera is suddenly causing new problems in these “other” crops but more to do with tighter regulatory demands. We now have to show picloram does not cause residue issues in following crops and are busy gathering data in what are called “confined rotational studies” to enable a wider choice of following crops on label such as beans and potatoes. Sufficient data is unlikely to be available before end of 2016.

For many of you with rotations based on cereals, winter or spring and oilseed rape this will not be an issue. Where it could be and cleavers are not the main target Dow Shield 400 is still an option but remember not to plant susceptible autumn-sown crops (e.g. winter beans) in the same year as treatment with Dow Shield 400 even though this seems unlikely! Dow Shield 400 does have approval on spring rape. Again in the unlikely event spring beans and peas are following rape, do not apply Dow Shield 400 any later than the end of July in the previous year.

Galera (MAPP 16413) has an EAMU approval on spring oilseed rape but beans etc. cannot be planted for 36 months as per label recommendations for winter oilseed rape.

Galera® ([old] MAPP 11961) already purchased from distribution by Jan 31st can still be used this spring. The Galera (MAPP 16413) following crop restrictions do not apply to this approval. However ploughing or thorough cultivation should be undertaken prior to planting beans peas, potatoes, carrots and other sensitive crops leguminous crops as damage could occur. Please heed warnings on label.

Fera Liaison does have a note of Galera (MAPP 16413) having following crop restrictions which should hopefully feed into the various crop recording systems for stewardship.

What can I plant after a failed winter oilseed rape crop?

We have been getting reports of rape crops having been eaten by pigeons. Options after a November – January application of Kerb® Flo 500 include April drilled spring oilseed rape at own risk. We advise ploughing but are aware of farmers who have successfully established spring rape without doing so. Following crops of beans or peas need a 10 week interval after application of Kerb Flo 500 to the previous oilseed rape.

Spring oilseed rape can be drilled if the oilseed rape crop has been treated with ASTROKerb®. Again own risk and just like Kerb Flo 500, we advise ploughing. Don’t drill spring beans or peas!

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If you require any further information please contact our Technical Hotline on 0800 689 8899 or your local Dow AgroSciences representative.

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Grassweed Emergence Monitor

19/01/2015

Spring Update 2015 – Report 7 – 19th February

Last autumn in conjunction with ADAS we started monitoring blackgrass emergence at two sites in key blackgrass areas of the UK – Cambridgeshire and Oxfordshire. We last looked at these sites in December.

Monitored plots have not received any herbicides at all and blackgrass counts are cumulative.

This week’s report:

December 2014 and January 2015 were 4-6°C warmer and drier than the 30 year average. The GEM sites have experienced around 16 frosts since the last report. Minimum air temperatures have been on average 0.4°C lower in Oxfordshire, than Cambridgeshire, but maximum air temperatures 0.1°C higher. Despite this, soil temperatures have been consistently up to 1.5°C lower in Cambridgeshire than Oxfordshire. Current temperatures are around 4°C in Cambridgeshire and 4.5°C in Oxfordshire. It was wetter in Oxfordshire than Cambridgeshire; since the last report sites have received 83 mm and 93 mm respectively.

Overall has been little change in blackgrass populations (i.e. winter kill – something we have seen in previous years) and no new emergence but in the early drilled, plants have added another 2 tillers.

All sown grassweeds are drilled at 500/m2. No herbicide treatment applied.

Current Advice for Grassweed Control in Winter Wheat:

Identify fields which would benefit from UNITE®. These are commonly fields with blackgrass and other grassweeds (ryegrass, bromes, wild oats) and/or broad-leaved weeds. UNITE is a flexible option for reduced tillage establishment for following crops of oilseed rape. Beans are also a following crop option

UNITE controls blackgrass up to GS 24

Sprays should be delayed until plants begin to grow actively. Grassweeds, in particular blackgrass will grow at a base temperature below 6°C however this growth is not active, it is slow. Where it is possible to travel, be vigilant if conditions are mild and favour active growth as these are good opportunities for grassweed control with UNITE. We could be moving into suitable conditions soon

UNITE, in common with all ALS-inhibitor graminicides, requires 2-3 days of “active” growth either side of the application. For this to occur, soil temperature measured at 10 cms deep need to be a minimum of 6°C ideally 8°C.

If soils are moist consider including additional residual where no pre-emergence has been applied or where it has been ineffective, or where further emergence of grassweeds is expected.

For optimal results:

On pre-tillering blackgrass apply UNITE in 130 – 150 litres of water per hectare as a FINE-MEDIUM spray with either CFF, VPFF or Defy Nozzles

For tillering blackgrass apply UNITE in 150 litres of water as MEDIUM spray with either CFF, VPFF or Twin fluid nozzle

Use Broadway® Star where ryegrass, wild oats and bromes are the driver-weed

Effective weed control depends on understanding specific opportunities in each crop in the rotation. Combating grassweeds requires a mix of approaches, and cultural control techniques should always be used in combination with a robust herbicide programme.

A crucial step to achieving successful control of headache grassweeds in winter wheat is to monitor when grassweeds emerge, so that post-emergence treatments can be applied when weeds are small and actively growing. Over the last three years, Dow AgroSciences’ Grassweed Emergence Monitor (GEM), in conjunction with ADAS, has been a useful tool for showing how quickly blackgrass, sterile brome and ryegrass grow away in the autumn.

This autumn we are focusing on blackgrass in winter wheat. Sites are in two key blackgrass areas of the UK – Cambridgeshire and Oxfordshire, where they will be monitored every two weeks.

GEM includes:

Blackgrass sown 500 seeds/m2 and a “natural” unsown blackgrass population

Two drilling dates – late September and late October

It is important to remember that germination of grassweeds will also be subject to local factors and the information provided by GEM should supplement but not replace field monitoring.

Wheat Bulb fly Pestwatch

Final Report – 26th February 2015

The latest HGCA Wheat Bulb fly survey indicated that only 1 field out of the 30 surveyed in eastern and northern England were above the 250 eggs/m2 economic treatment threshold for early/mid-autumn drilled crops. This is the joint lowest recorded since 1984. For late November-March drillings, a lower threshold of 100 eggs/m2 is applicable. In the north of England, 53% of sites were above this level but, in the east of England, only 13% of sites were above this level.

The full survey results are available on the HGCA website www.hgca.com.

This week’s report

Hatch is progressing in the east, where we now have approximately 50% hatch and second instar larvae at all sites. In contrast hatch in the north is still at an early stage of egg-hatch with no plant invasion this week.

Date: 23rd February 2015

Site

Soil

Total number of viable eggs (inc. hatched)

Percent hatched

% Tiller infested

1. Ixworth, Suffolk

Mineral

16

50.0

1.6

2. Terrington St Clement, Norfolk

Mineral

12

58.3

1.9

3. Littleport, Cambridgeshire

Organic

9

44.4

2.5

4. Fimber, North Yorkshire

Mineral

37

2.7

0.0

5. Huggate, East Yorkshire

Mineral

10

10.0

0.0

What does this mean for you?

Egg-hatch sprays in the east will now have limited effect. In contrast egg-hatch sprays in the north are still likely to be effective. Application is now being made difficult by recent rain and wet soils.

Where you are able to travel, for those fields at risk apply Dursban WG at 1.0 kg/ha in 200 to 1000 litres per hectare of water.

In the absence of egg counts for specific fields, risk assessments for treatment must be made on the basis of locality, previous cropping, drilling date, plant population, tillering and soil type. Use Risk Assessment Charts to identify fields at risk.

An interval of 14 days must be observed between applications of Equity or Dursban WG and UNITE® or Broadway® Star, regardless of weather conditions. For Atlantis WG and similar approved formulations leave a longer interval of 4 weeks for crop safety.

For other compatibilies please refer to Equity or Dursban WG tank-mix advice. If necessary, Dursban WG or Equity can be applied to frosty ground but should NOT be tank mixed.

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Kerb Weather Data

20/11/2014

Final Report – week-ending 21st November 2014

Soil temperatures across much of the country have declined and where able to travel, growers should consider making their Kerb® Flo 500 and ASTROKerb® applications. Applications of Kerb Flo 500 or ASTROKerb must only be made after taking all necessary precautions to avoid contaminating surface waters. If heavy rain is forecast the responsible course of action would be to delay the application. The longer the period of time, between application and a severe rainfall event the less likely it is that Kerb will be lost through surface run off and drain flow

For optimal blackgrass control Dow AgroSciences recommend Kerb Flo 500 applications are made when soil temperatures have got down to 10°C and falling, and there is sufficient soil moisture in the soil for plant uptake. Both these criteria are rarely met before November. This advice has been proven in extensive trials over many variable autumns. Similar advice would apply to ASTROKerb

Check out application conditions for your local postcode

Click on the My Farm LifeCycle to check out forecast conditions for optimizing Kerb Flo 500 and ASTROKerb applications on farm. Simply enter your postcode in the banner and click GO to view the results.

FAQs

Do I need a dry-leaf for application?

The propyzamide active in Kerb Flo 500 is soil acting so spraying wet weeds at run-off or light rainfall after application is not an issue. Ideally, the rainfastness of ASTROKerb is 1 hour for the aminopyralid element. Spraying on a drying leaf is OK but if rainfall falls within 1 hour and causes run-off efficacy may be reduced. All applications should be made with due regard to water stewardship, i.e. do not spray where there is a risk of run-off to adjacent watercourses.

Can I apply Kerb Flo 500 in a frost?

Kerb Flo 500 may be applied in frosty conditions but avoid application onto frozen ground where subsequent rainfall could result in run-off into watercourses. For ASTROKerb please ensure frost is off the target broad-leaved weed.

Download Topic Sheet 16 “Advice for Blackgrass Control in Oilseed Rape” for further advice.

Product Manuals

Topical questions

We have been receiving reports of sow thistles germinating in rape. Galera® ([old] MAPP 11961) purchased from distribution by Jan 31st can still be used throughout 2015 up to 30th September, (in effect this spring) including January/February.

Galera oilseed rape herbicide has now been re-registered as MAPP number 16413. In line with all other clopyralid containing products in the UK, autumn use is now withdrawn. New label Galera (MAPP 16413) can only be used from 1st March 2015 and will have no autumn approval.

Options after a November – January application of Kerb® Flo 500 include April drilled spring oilseed rape at own risk. We advise ploughing but are aware of farmers who have successfully established spring rape without doing so. Following crops of beans or peas need a 10 week interval after application of Kerb Flo 500 to the previous oilseed rape.

Spring oilseed rape can be drilled if the oilseed rape crop has been treated with ASTROKerb®. Again at own risk and just like Kerb Flo 500, we advise ploughing. Don’t drill spring beans or peas!

Consider including additional residual (e.g. 240g ai/ha flufenacet till end December; 120 g ai/ha flufenacet after 1st January till around end February) particularly where no pre-emergence has been applied or where it has been ineffective, or where further emergence of blackgrass is expected.

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